Elli Stark, a Human female, was born to Arris Rossum and a man who was not her husband. Although Arris was married to Iaco Stark, Iaco raised Elli as his own, keeping the truth of her parentage hidden from her. She had a half-brother named Iaclyn Stark.
Even though Iaco Stark was not her biological father, Elli Stark was known as his and Arris Rossum's daughter. Her mother engaged in an affair, resulting in Elli's conception.
Iaclyn Stark, her brother, was favored by their father, and Elli grew up in his shadow. Despite this, they maintained a positive relationship throughout their childhood until circumstances forced their separation later in life. Following the presumed death of her father in 5 BBY, Elli and her stepmother, Dah'lis, received only a small portion of the inheritance, with Iaclyn claiming the majority. He intended for his sister to marry a wealthy and influential man, but she refused.

At a ceremony held at the Imperial embassy on Etti IV in 3 BBY, she encountered Jahan Cross, a covert Imperial Agent. Cross intervened when he noticed Verpel was bothering her, introducing himself as her fiancé to deter the man. Grateful for Cross's help, Elli confided in him about her family and situation. Upon seeing her brother approach, she excused herself and returned to her quarters within the Stark Compound. Cross later visited the Compound with Dah'lis and witnessed her murder. As he was being escorted away by Espos, he encountered Elli in the hallway. He attempted to speak with Stark, but the Espos assaulted him. After retaliating and disabling his escort, Stark advised him to escape through the garage. Cross commandeered a speeder and attempted to flee through the house. When Myrsk tried to shoot him down, Stark intervened, emphasizing the potential cost of the damages if he succeeded.
After staging his own death to shake off the pursuing Espos, Cross sought out Stark in her bedroom at the compound, assuring her that he was not responsible for her stepmother's death. Believing him, she assisted him in uncovering information about the Iron Eclipse project. Unbeknownst to them, Iaclyn's droid, Majordomo, was spying on them and reporting back to his master. Iaclyn instructed the droid to eliminate Cross while ensuring Elli's safety. Cross neutralized the droid and arranged transportation aboard the Millennium Falcon to the Eclipse space station to further his investigation. Once aboard the freighter, Elli expressed her doubts about the ship's airworthiness. Solo reassured her that it was safe. After departing Etti IV, Cross and Stark retreated to one of the ship's cabins so she could tend to his wounds from his encounter with Majordomo. Cross revealed his history to Elli, explaining his devotion to the Empire. They then shared a kiss. Upon reaching the space station, Stark attempted to authorize their landing but was denied, causing Vulture droid starfighters to attack the Falcon. Cross found a landing bay, and he and Stark departed the Falcon, allowing it to escape and draw off the droid starfighters. She and Cross confronted Iaclyn but were subdued by droids under control of the Iron Eclipse virus. Iaclyn explained to Elli that she put herself in danger by coming to the space station. He revealed that she was not the daughter of Iaco Stark, but rather the result of an affair Arris Rossum had. Therefore, Iaco Stark felt no connection to her and would not hesitate to kill her. Iaclyn explained that his attempts to arrange a marriage were to get Elli safely away from the Starks. Elli witnessed the murder of her brother when Iaco appeared behind Iaclyn and stabbed him through the chest. Iaco greeted her and told her he owed her nothing and was going to kill her. Elli grabbed a blaster and retreated with Cross to the exit of the room where they were confronted by a reprogrammed IN-GA.
While droids held Elli captive, Iaco observed Cross and IN-GA in combat. As IN-GA departed to disable the repulsorlift generators, Iaco commanded all the droids to halt, freeing Elli. Following Cross's instructions, she fled to the landing pad and attempted to contact the Millennium Falcon for extraction. After Cross incapacitated Iaco, he and Elli jumped from the collapsing space station onto the Falcon, entering through the dorsal hatch. Elli proceeded to the cockpit and requested a jump to hyperspace, but Solo informed here they had to clear the planet's gravity well first. When IN-GA contacted the Falcon and explained she was trapped on the dying space station, Elli asked if they could go back and retrieve her. Solo stated that they couldn't for safety reasons, but there might be a chance to rescue the droid by using the ship's tractor beams. When Cross rejected that plan, stating it was too dangerous, Elli tried to sentimentally persuade Cross. He responded that Inga was "simply a droid. A machine."
Once they had escaped Reltooine's orbit, Elli and Cross sought refuge in one of the Falcon's cabins. She reiterated Cross's promise to help her leave the Corporate Sector and suggested a desire to become a spy on Coruscant, emulating Cross's profession. They then shared another intimate kiss.